The Transpacific Yacht Race is an offshore yacht race starting off Point Fermin near Los Angeles and ending off Diamond Head in Honolulu, a distance of around 2,225 nautical miles. Started in 1906, it is one of yachting's premier offshore races and attracts entrants from all over the world. The race is famous for fast downwind sailing under spinnaker in the trade winds. The current mono-hull elapsed time record of 7 days, 11 hours 41 minutes and 27 seconds is held by Roy E. Disney's Pyewacket, a 73 foot maxi ultralight designed by Reichel/Pugh. In 2005, Hasso Plattner's Morning Glory-a maxZ86 from Germany-was the scratch boat when it led a five-boat assault on the record for mono-hulls in 6 days 16 hours 4 minutes 11 seconds while collecting the Barn Door slab of carved koa wood traditionally awarded to the monohull with the fastest elapsed time.
Most offshore racing involves the interpretation of weather charts, forecasts, visible conditions and the use of this information to make tactical decisions.
The trade winds are a pattern of winds that are found in bands around the Earth's equatorial region. The trade winds are the prevailing winds in the tropics, blowing from the high-pressure area in the horse latitudes towards the low-pressure area around the equator. The trade winds blow predominantly from the northeast in the northern hemisphere and from the southeast in the southern hemisphere.
Their name derives from the Middle English 'trade', meaning "path" or "track," and thus the phrase "the wind blows trade," that is to say, on track.
In the zone between about 30° N. and 30° S., the surface air flows toward the equator and the flow aloft is poleward. A low-pressure area of calm, light variable winds near the equator is known to mariners as the doldrums. Around 30° N. and S., the poleward flowing air begins to descend toward the surface in subtropical high-pressure belts. The sinking air is relatively dry because its moisture has already been released near the Equator above the tropical rain forests. Near the center of this high-pressure zone of descending air, called the "Horse Latitudes," the winds at the surface are weak and variable. The name for this area is believed to have been given by colonial sailors, who, becalmed sometimes at these latitudes while crossing the oceans with horses as cargo, were forced to throw some overboard to conserve water.
The surface air that flows from these subtropical high-pressure belts toward the Equator is deflected toward the west in both hemispheres by the Coriolis Effect. Because winds are named for the direction from which the wind is blowing, these winds are called the northeast trade winds in the Northern Hemisphere and the southeast trade winds in the Southern Hemisphere. The trade winds meet at the doldrums. Surface winds known as "westerlies" flow from the Horse Latitudes toward the poles. The "westerlies" meet "easterlies" from the polar highs at about 50-60° North and South.
Tropical Weather Cell
The intertropical convergence zone (ITCZ) is a dynamic weather area located near the equator. Sunlight at the equator warms the air, making it rise and thereby creating low pressure at the equator, along with rain-producing cumulonimbus clouds. The rising air eventually cools and sinks back to the surface at latitudes roughly 30° north and south of the equator. The sinking cool air creates high-pressure systems that keep those latitudes relatively dry. The sinking air is drawn back to the low pressure near the equator, creating a flow of air known as the trade winds. Eventually, the trade winds converge near the equator and create the ITCZ.
Chasch Mer’s route from her home in Hawaii to California in May of 2007.
No comments:
Post a Comment